轻质油藏注空气提高采收率技术适应性探讨

Feasibility study on high-pressure air injection for EOR in light oil reservoirs

注空气技术是轻质油藏提高采收率的一种有效手段,该技术的驱油机理与地层原油氧化反应息息相关。本文通过调研国内外注空气技术研究,阐述了轻质油藏注空气技术的应用优势,分析了含水饱和度与地层剩余油量对该技术驱油效果的影响,基于氧化反应机理与矿场应用探讨了该技术在轻质油藏的适用性。研究表明:注空气技术适用于水驱后油田进一步提高采收率;地层剩余油量过低会影响注空气驱油效率,此时可通过适当提高注入气中N2含量或向注入气中添加吸附颗粒,来保证原油氧化反应的平稳进行,提高驱油效果。此外,矿场应用中应重视可能发生的气窜问题。

Air injection has been considered to be an effective enhanced oil recovery（EOR）process for light oil reservoirs.During the process,compressed air is injected into a high-temperature light-oil reservoir,and the oxygen in injected air is intended to react with a fraction of reservoir oil and results in an in-situ generation of flue gases and steam.Therefore,the residual oil that is immobilized by water flooding could be driven towards producer wells.The displacement mechanisms are highly related to the oxidation behavior of crude oil.Relevant studies were involved in this paper to discuss the merits of high-pressure air injection（HPAI）in light oil reservoirs,and to demonstrate the influence of water saturation and residual oil volume on displacement efficiency.According to the investigation,a feasibility study of HPAI was conducted based on the oxidation mechanisms associated with field applications.The results shows that air injection could be technically applied for EOR in water flooded reservoirs,especially in those highly water-saturated reservoirs.An insufficient residual oil volume could universally lead to low displacement efficiency;under this circumstance,adding an appropriate content of nitrogen or absorbing particles into injected air could stabilize oxidation reaction and thus improve displacement efficiency.In addition,there still exists sorts of security concerns during field applications,so more emphases should be placed on the air breakthrough in the producers.